1. Field of the Invention
The present invention relates to a sheet material handling apparatus. Specifically, the present invention relates to a sheet material handling apparatus having a plurality of feeders which deliver sheet material to a conveyor in an aligned relationship.
2. Description of the Prior Art
Collators for signatures, that is a single flat sheet, a single folded sheet or a plurality of folded sheets, are well known in the bindery art. A collator for signatures typically includes a plurality of feeders. Each of the feeders includes a hopper for supporting a stack of signatures so that each signature is supported in a generally horizontal orientation.
Each hopper may be supplied with signatures by a hopper loader. The hopper loader receives stacks of signatures, usually in a bundle form. The loader forms a stream of signatures in a continuous overlapped, or "shingled", relationship. The signatures are then delivered to the hopper one at a time to form a stack of signatures on a horizontal hopper support. Two such hopper loaders are disclosed in U.S. Pat. Nos 3,904,191 and 3,945,633.
In addition to a hopper, each of the signature feeders may include a rotatable drum. Grippers mounted on the drum remove one signature at a time from the bottom of the hopper as the drum rotates. The grippers release the signature to deposit, or deliver, the signature onto a conveyor which is moving along a path below the drum.
As the conveyor travels along the path below other feeders, additional signatures are deposited thereon to form a pile, or group, of signatures. The group of signatures can then be bound together to form a book, pamphlet, magazine, or the like. Two such known signature collators are disclosed in U.S. Pat. Nos. 3,525,516 and 3,825,247.
When the groups of signatures are bound together, it is imperative that the edges of the signatures are aligned. If the edges of the signatures are misaligned, the edges of the book, magazine, or pamphlet will not be uniform. Misalignment of the edges of the signatures may be the result of not having edges of the signatures properly aligned in the hopper.
When a signature is misaligned in the hopper, the misaligned orientation of the signature will be maintained as the signature is deposited onto a group of signatures on the conveyor. If a completed group of signatures containing the misaligned signature is bound, the resulting book, magazine or pamphlet will be unsatisfactory in appearance.